There is of course that any rash should really be evaluated by a professional to rule out it being anything serious.
99% of rashes are nothing and are just caused by allergies or coming into contact with things your skin doesn't like, but they can also indicate serious conditions, with meningitus being the most obvious.
My guess is you didn't come on here to ask how to get rid of it, but wanted to know if it was serious without wanting to sound like you're worried about it. It most probably isn't serious, but unless you have had this kind of rash a lot before and know what causes it (I'm guessing not by the way the thread is written) then I would get to a GP ASAP and rule out it being anything serious.
Might sound like I am being over the top here but it really isn't worth risking a serious condition for the sake of a couple hours at the GP. Plus, after he has identified it and ruled out it being serious, he is also going to know exactly how to treat it, rather than people on here, who, with all due respect haven't seen the rash, do not know your allergies, personal circumstances etc, and can only offer very general advice which you can find on google.
I have asked many questions on RAWK and got many helpful answers, however if I was concerned about my personal health I would go to a qualified professional who could evaluate my situation, not the off-topic section of RAWK.